How to assess impact of deprecating VM image?

For a .NET 6 Windows Server 2022 Azure Marketplace image that is being deprecated, the impact is governed by the general Azure image deprecation behavior.

Key behavior for the existing VM:

1. VM continues to run normally
   • Once created, a VM boots from its OS disk, not from the original Marketplace image. Deprecation does not affect running VMs.
   • Start, stop, restart, deallocate, and redeploy operations continue to work as usual for images without a purchase plan (which includes standard Microsoft Windows Server images).
2. What “disruptions” means in this context For Microsoft first-party images (Windows Server, etc.) that do not require a purchase plan:
   • Creating new VMs from the deprecated image is blocked after the enforcement date.
   • Reimage of the VM is blocked, because reimage needs the original source image.
   • For VM scale sets, scale-out that requires creating new instances from that specific deprecated version can be blocked. Scale-out using “latest” or automatic OS upgrades can still work.
   • Backup and restore, including restore-to-new-VM, continue to work for images without a purchase plan.
   In other words, the “disruption” is to operations that depend on the original Marketplace image (new VM creation, reimage, some VMSS scale-out scenarios), not to the day‑to‑day running of the existing VM.
3. Security and maintenance updates
   • Image deprecation itself does not change how the VM receives OS or application updates. The VM continues to get updates via the normal Windows Update / patching mechanisms configured on that server.
   • Deprecation mainly means that particular image version is no longer offered for new deployments; it does not inherently compromise the security of an already-running VM.
4. When migration is or is not required Migration is not required if:
   • The image does not require a Marketplace purchase plan (typical for Microsoft Windows Server images), and
   • There is no need to reimage the VM, create new VMs from that exact image, or scale out VM scale sets based on that specific version.
   Migration is required if:
   • There is a need to keep creating new workloads from that image after the enforcement date, or
   • VM scale sets must scale out using that specific image version, or
   • The image required a purchase plan (not the case for standard Windows Server images) and operations like backup restore, reimage, or scale-out must remain guaranteed.
5. Recommended practical actions
   • Treat the existing VM as safe to continue running; no immediate breakage is expected from deprecation alone.
   • Plan that:
     • New VMs should be created from a newer, supported image.
     • Reimage operations on this VM will no longer be available after enforcement.
   • To avoid future dependency on Marketplace image availability, consider capturing the workload as a custom image in Azure Compute Gallery; custom images are not subject to Marketplace deprecation.

References:

• Deprecated images FAQ
• Key points
• Which operations are affected by image deprecation?
• What is the deprecation timeline and how does it affect my workloads?
• When should I migrate my VMs or virtual machine scale sets to a different image?